Stems...

Lookin to do some upgrading on my iggy super, and after demoing a mongoose nugget, i have the desire to switch to a shorter stem. The stem that i currently have on my ride is the truvativ XR riser stem (120mm) and sometimes it feels sorta akward when i am doing jumps or drops. So i was thinking about decreasing my stem to a 90mm gravity gap os. So would this solve my problem ? and are there any positves/negitives to doing this? i would think about buying an even smaller stem, but i am afraid that the bike wouldnt fit the same, and my performance would suffer when i am XC riding. so i figure a 90mm stem might offer the best of both worlds... any opinions?

punch in what you have right now... guesstimate where you want the bars to be and play with the numbers till you get it about where you want it, buy a cheap stem and try it out and adjust from there...

Stems

My 07' Giant Trance 2 came with a 105mm stem and I felt stretched out when riding. I wanted to feel a little more upright over the handlebars and dropped down to a 90mm stem. My bike and riding feel a lot better overall now that the bars are closer. It's similiar to my old BMX 24" cruiser (but not quite). But it's all a matter of personal preference.

My bike had a 90 mm stem, I dropped to a 65 mm feels much better for drops and jumps. Feels almost perfect on small drops and down hills. I may go shorter to a 30 mm.
It's really like he said, personal taste.

When I built up my Iggy, I started with a 90mm stem on a 20" frame. I dropped down to a 65mm and like that alot.
It really depends on how you need the bike to fit you and how you ride it. 80 or 90 would be a good starting point.
I've swapped to shorter stems on all of my bikes. Even my commuter. I have 2 50mm stems, a 60mm and a 65mm. If you are leaning more towards the XC side of things I'd stay in the 80-90 range.

I just put a 65mm stem on my bike from a 90mm. I can still climb just as well if not better now because i can pull my front end up easier to clear obstacles. I was always sliding forward on my seat is the reason i went shorter.

I am not familiar with a iggy super, but a 90 mm stem would be a great stem to try. A 120mm stem is very cross-country and would be considered huge for a AM bike. I would recommend you try the 90mm for a while and if you like that then move to a 70mm, but to go from a 120mm to a 70mm would be too big a jump.

Personally, I ride a 50 inch zero rise stem with a 2 inch riser bar on my trail bike. It's all about personal preference though. These kind of things are very subjective. I may lose a little something in the uphills but I didn't ride my longer stem long enough to know one way or the other. It feels awesome on the downhills though, stable and very confidence-inspiring. Plus it just looks freaking cool.